As an owner of a 4B-ST I am biased...
I would rate the three in order of preference with the Bryston first then Aragon, then Parasound. Now, the 4B-ST would have stiffer competition if we were to consider the Aragon 8008BB, Classe CA-200/201, Marsh A400 and a few others. But if this is the three we are working with the 4B-ST is the hands down winner for build quality, sonics, after sales service and the best warranty in the biz!
I would rate the three in order of preference with the Bryston first then Aragon, then Parasound. Now, the 4B-ST would have stiffer competition if we were to consider the Aragon 8008BB, Classe CA-200/201, Marsh A400 and a few others. But if this is the three we are working with the 4B-ST is the hands down winner for build quality, sonics, after sales service and the best warranty in the biz!